Hi Koonal, Sorry for not exact suggestion.
I hope that combination of `annotate` and `values` will be helpful, see this link for more detailed explanation <https://docs.djangoproject.com/en/1.10/topics/db/aggregation/#values>. Pleas try something like following: cases = HeartFlowCase.objects.values(‘all fields required in your view’). annotate(min_deadline=Min('data__deadline')).order_by('min_deadline') It is the Todor's suggestion extended with value method run. I believe that you need `GROUP BY` in your SQL query and it generated by `values` as said in Django documentation. On Fri, Aug 19, 2016 at 7:10 PM, Simon Charette <[email protected]> wrote: > For reference there's a Django ticket to suggest using this technique. > > Cheers, > Simon > > [1] https://code.djangoproject.com/ticket/19842 > > > Le jeudi 18 août 2016 02:20:34 UTC-4, Todor Velichkov a écrit : >> >> Another solution would be to annotate min/max deadline date and order by >> the annotation. Something like: >> >> cases = HeartFlowCase.objects.all().annotate(min_deadline=Min('data_ >> _deadline')).order_by('min_deadline') >> >> >> On Thursday, August 18, 2016 at 7:59:19 AM UTC+3, Constantine Covtushenko >> wrote: >>> >>> Hi Koonal, >>> >>> As said in django doc >>> <https://docs.djangoproject.com/en/1.10/ref/models/querysets/#order-by> you >>> can use `distinct()` to remove duplicated rows from first query. >>> >>> I believe with this your pagination should works as expected. >>> >>> Regards, >>> >>> >>> On Thu, Aug 18, 2016 at 2:58 AM, Koonal Bharadwaj < >>> [email protected]> wrote: >>> >>>> Hello, >>>> >>>> The issue: >>>> >>>> When trying to order_by on a related model duplicate entries are >>>> created. I solved this with an OrderedSet that is applied after paginating >>>> ( >>>> http://code.activestate.com/recipes/576694/). However, when I try to >>>> paginate the queryset, all the results are not returned. It's missing a few >>>> table rows. >>>> >>>> Models: >>>> >>>> class HeartFlowCase(models.Model): >>>> """ >>>> >>>> A Hearflow Case. >>>> >>>> This serves at the true state of a case as it is processed through the >>>> system. >>>> It also holds the results of each step of the processing. >>>> >>>> """ >>>> >>>> # Primary >>>> hf_id = models.CharField('HeartFlow ID', max_length=200, blank=True, >>>> unique=True) >>>> canonical_data = models.ForeignKey('cases.CaseData', to_field='uuid', >>>> related_name="canonical_data") >>>> >>>> >>>> class CaseData(models.Model): >>>> """ >>>> Extracted and computed values related to a single processing run of a >>>> case. >>>> >>>> A HeartFlowCase can have multiple runs associated with it. >>>> The one which is accepted to be the "clinically accurate" one is the >>>> one referred to as 'canonical_data' by >>>> the HeartFlowCase itself. >>>> >>>> """ >>>> >>>> # Primary >>>> heartflowcase = models.ForeignKey(HeartFlowCase, related_name='data', >>>> blank=True, null=True) >>>> uuid = models.CharField('Case Data UUID', max_length=200, blank=False, >>>> null=False, unique=True) >>>> deadline = models.DateTimeField('Deadline', blank=True, >>>> default=get_default_deadline) >>>> >>>> >>>> As you can see, there is a ForeignKey to canonical CaseData from >>>> HeartFlowCase and a ForeignKey to HeartFlowCase from CaseData. So you >>>> can have multiple CaseDatas per HeartFlowCase. >>>> >>>> Structure: >>>> >>>> HeartFlowCase >>>> | >>>> data - CaseData1 >>>> \ >>>> \ CaseData2 >>>> >>>> >>>> For example: >>>> >>>> Total number of HeartFlow objects are 5 with 2 CaseDatas each. If I >>>> order_by deadline on CaseData as: >>>> cases = HeartFlowCase.objects.all().order_by(data__deadline) >>>> this returns duplicates since there are multiple CaseDatas, which is >>>> fine. Now I try and paginate it by applying: >>>> >>>> paginator = Paginator(cases, 2) >>>> cases = paginator.page(1) >>>> >>>> Now the SQL query has a LIMIT and OFFSET given. If the order_by gives >>>> duplicate HeartFlowCase objects this hits the LIMIT number and the results >>>> that are returned are missing a HeartFlowCase object. So if 2 duplicates >>>> are returned per case after applying the OrderedSet I get only one case >>>> back and missing one case since it was never returned from the database. >>>> As I goto the next page: >>>> >>>> cases = paginator.page(2) >>>> >>>> that missingHeartFlowCase object that was not returned from the first page >>>> queryset is lost forever and is never displayed. >>>> >>>> >>>> I hope this is clear. Please let me know if I can clarify further. Any >>>> help would greatly be appreciated. Thanks. >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Django users" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> Visit this group at https://groups.google.com/group/django-users. >>>> To view this discussion on the web visit https://groups.google.com/d/ms >>>> gid/django-users/61ec03f6-3325-49fe-bcdc-a7ca50784dc0%40goog >>>> legroups.com >>>> <https://groups.google.com/d/msgid/django-users/61ec03f6-3325-49fe-bcdc-a7ca50784dc0%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/django-users/92915a0e-3cc4-4495-ba69-56511c781121%40googlegroups.com > <https://groups.google.com/d/msgid/django-users/92915a0e-3cc4-4495-ba69-56511c781121%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. 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